Poking holes in the Gravity trailer with NASA’s help

We sit down with the guy who trains spacewalkers to see what's right—and wrong.

I haven't seen Alfonso Cuarón's Gravity yet, but I want to. The movie will enter general release here in the US on October 4. It stars George Clooney and Sandra Bullock as two astronauts having what looks to be a really, really bad day in space. Trailers for the movie show them flying around in their space suits, yelling and crying and dodging debris from exploding satellites and space ships and space stations, all lit by a beautifully rendered and untouchably distant Earth in the background.

The director and the studio have taken great pains to recreate the experience of operating in microgravity as accurately as possible. Cuarón consulted with NASA astronauts on the particulars of moving in microgravity, and, according to the NY Daily News, the movie's production designers studied thousands of NASA photographs in order to make their vision of space look authentic.

When asked how far that commitment to verisimilitude stretched, though, Cuarón said that while the movie strives for accuracy, "it would be disingenuous to say we did it 100 percent, because this is a movie, and we needed to take certain liberties."

The five minute-plus extended trailer for Gravity. Keep this video handy, because we're going to give it the MST3k treatment in just a moment.

There was a five-minute "extended trailer" for the movie published last month. It certainly had some gripping visuals, but the longer it went on, the deeper my frown became. I don't claim to be an expert, but the stuff that George Clooney and Sandra Bullock were doing on the screen just didn't look right. Certainly cool, but not right.

But this is Ars, and on certain things, we have the hook up. I may not be the expert, but I knew someone who was, and I was going to ask for his official opinion on that extended trailer.

The man who makes the plan

The last time I talked with Zeb Scoville was at NASA's Neutral Buoyancy Lab, the enormous indoor pool where NASA trains its astronauts on how to spacewalk—or, more properly, how to function during extravehicular activity, or EVA. Scoville is the EVA task group lead at the NBL, and he is responsible for managing the teams that figure out how EVAs work. If an EVA's goal is to replace a part outside the space station, for example, Scoville figures out exactly what the astronauts need to do to replace the part, including the physical movements they need to make. His team is made up of actual NASA flight controllers—during training at the pool, they run the simulations, and during the actual missions, they're manning the consoles in Mission Control.

Enlarge/ NASA EVA Task Group manager Zeb Scoville, standing in one of the test coordinator control rooms at the Neutral Buoyancy Laboratory. Visible behind him is the NBL pool.

Steven Michael

If anyone could shed some light on the accuracy or inaccuracy of Clooney and Bullock's space antics, I figured Scoville would be the man. After a quick call to NASA's press office to arrange some time to talk, we sat down together to watch our way through the trailer.

Problem: debris

The trailer kicks off with an EVA in progress, and a radio-distorted voice is heard calling for an abort. It becomes clear that the message is directed at some astronauts working on something outside their spacecraft. It looks like they're repairing the Hubble Space Telescope, though it might be something else—for instance, some KEYHOLE reconnaissance satellites are said to share the Hubble's external form factor. Whatever it is, the astronauts are outside with big debris incoming, which means they're in trouble.

Enlarge/ Screencap from the trailer, showing the start of a giant debris storm. Note the monstrous size of the piece of debris near frame center.

Warner Bros

Right away, the sheer size of the debris gave us pause. NASA relies on US Strategic Command's big radars to keep constant radar watch on its vehicles, and the chunks shown on-screen are far larger than the minimum size that USSTRATCOM would notice. "Part of the procedure for getting ready for an EVA would include checking for debris like this, wouldn't it?" I asked.

"Right—we have a process that's known as a 'certification of EVA readiness,'" answered Scoville. "We have the EVA community come together, and they'll present a lot of the technical analysis, and we give our community-wide consensus for a 'go' for the EVA." Scoville explained that this analysis includes an assessment of the risk of encountering orbital debris during the EVA. Space isn't empty, especially at the International Space Station's low altitude, and there's always the chance that there'll be a "conjunction," NASA-speak for a potential collision between debris and a vehicle or astronaut. Debris risk is assessed in terms of the potential damage—whether the expected amount of debris could cause a suit leak small enough to survive (which would terminate the mission), or whether it could cause loss of a spacecraft or even astronaut lives.

"The debris they have there is orders of magnitude larger than what you need to create a very catastrophic puncture in a space suit. For comparison, if you have up to about an eighth inch of a hole in an EMU"—that's Extravehicular Mobility Unit, NASA's acronym for a spacesuit—"it has emergency oxygen systems which can feed that leak and maintain pressure for about 30 minutes to get you back inside the airlock and repress the airlock. Above about an eighth of an inch, and it can't maintain pressure."

"Is there a procedure for what to do if that happens?" I asked. "Like, you stick your finger in the hole or try to squeeze the leak closed?"

Scoville responded in the negative because of the spacesuit's many-layered structure. "On the inside, you have the bladder layer, that actually maintains the pressure of the suit. Beyond that there's the restraint layer, and then you have a neoprene layer, and beyond that the insulation mylar layers for heat rejection, with layers of scrim in between for separation, then the white Ortho-Fabric on the outside. No matter how much you squeeze or push on the outer layer, you're not getting to the inner layer where the bladder is. You wouldn't be able to seal that with a gloved hand with 4.3 pounds of pressure trying to get out of the suit."

Although an EVA wouldn't be allowed to happen under such conditions, Scoville speaks up here and lets me know that he's actually Googled a plot summary of the movie in preparation for our talk. The debris in Gravity actually comes from an event that occurs after the EVA has started. Under such circumstances, the EVA would indeed be terminated, just as is depicted in the trailer. I stow my nerd rage, and we continue.

Problem: Clooney's jetpack

After the debris zips past, intrepid astronaut George "The Chin" Clooney comes in frame, sporting a very cool space jetpack. There's a problem with that backpack, though—nothing like it exists in NASA's active inventory anymore. To me, it looks like Clooney's character is supposed to be wearing a Manned Maneuvering Unit or MMU, a piece of equipment developed for shuttle astronauts to use while repairing satellites. The MMUs worked great, but they weren't used very much, and NASA discontinued flying them in the 1990s. They weren't re-introduced for use on the International Space Station because they're too large and bulky.

I point this out to Scoville. "Yeah," he replied. "It looks not quite like a MMU, but it's something close to it. Those things, the manned maneuvering units, are no longer used. In some of those shots, it looks like a cross between a MMU and a thing we call SAFER, which stands for 'Simplified Aid for EVA Rescue,' which is similar to a MMU—except it doesn't have the same level of redundancy, it's not as large, the joystick is a little different, and it doesn't hold as much gas."

The SAFER backpacks are for astronauts working around the International Space Station, and as the acronym suggests, they're intended to be used in case an astronaut accidentally drifts away from the station. Scoville explains that the little safety jetpack has 24 thrusters powered by the venting of compressed nitrogen gas, and it can accelerate an astronaut up to about 10 feet per second. The SAFER also has a smart gyro-based stabilization system that will automatically stop an astronaut from tumbling. However, these packs aren't intended to be used as the primary means for flitting about outside. The limited amount of delta-v the backpacks can impart is more than enough to stop a drifting astronaut, but the amount of propellant is very limited.

SAFER backpacks weren't used on shuttle missions, either: "On shuttle missions, when they weren't docked to station, they didn't need this—they could just fly the shuttle after them to pick them up if they fell off." This provides one explanation for why Clooney's character is wearing a jetpack and Bullock's character isn't—when we meet her in a moment, she's strapped into the foot restraints at the end of the space shuttle's remote manipulator arm, busily working away at repairing the telescope.

166 Reader Comments

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

Usually you see this stuff after the movies are actually out though - not before they are even in general release...

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

Because, like with Sunshine, if a movie is couched as realistic, and 'looks' realistic, then the layman will assume it is realistic. This annoys those who know just how wrong things actually are, especially when things are needlessly inaccurate. If your error could have been solved by 30 seconds on Wikipedia, then that's not making a vital deviation to allow the plot to advance, it's just not caring. And not caring about your film is rarely the sign of a good film.

Also, the movie just seems a bit insulting to astronauts, assuming they're panicky everymen. Whcih doesn't hold up well compared to reality, e.g. the Italian astronaut who, on his second ever spacewalk almost drowned in his suit due to a leak and who, whilst cut off from radio contact and with near-zero visibility, followed procedure and returned to the airlock to await his buddy.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

I have seen this movie already and I understand it is not meant to be 100% accurate, however there are some events in this movie so unbelievable it removes you from being immersed in the story and makes you very consciously aware you are watching a movie. They need to maintain suspension of belief enough for people to follow along for the ride and not just watch someone take the ride.

I don't want to spoil anything but I will say Sandra Bullock's character should have died many many times.

The last part of the article got me. No wonder we don't have much to show for space wise in the last decades. Humans are just too dainty. And we do not seem to be able to stomach any losses anymore (not complaining ). So how about killing human space exploration and getting robots ready. And after we have completely robotized space exploration get rid of all the stupid meetings and beaurocracies that seem to smother NASA and do some cool stuff again.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

Usually you see this stuff after the movies are actually out though - not before they are even in general release...

I seem to remember climate scientists talking about the film before it was generally released.

Just on the orbital dynamics, was it the actual Hubble Space Telescope they were servicing? If it was a fictional one or a spysat with an orbital plane closer to the ISS's, would that make it more believable? Or are all the Keyhole sats in HST-style orbits? (Maybe all the spysats are closer to polar orbit, which would give an even bigger orbital plane differential?!)

Whatever. For drama, no matter how realistic you make things, in the end, things have to move at the speed the plot requires and they are not subject to the normal laws of physics.

Finally, a question for the people who know: how do the suits communicate? Is it point to point, or do they need to relay through the shuttle/ISS?

The last part of the article got me. No wonder we don't have much to show for space wise in the last decades. Humans are just too dainty. And we do not seem to be able to stomach any losses anymore (not complaining ). So how about killing human space exploration and getting robots ready. And after we have completely robotized space exploration get rid of all the stupid meetings and beaurocracies that seem to smother NASA and do some cool stuff again.

The problem isn't so much the losses - although that's very tragic - as it is the cost in replacing astronauts. Consider how many hours training the average astronaut has to go through just to get to the point they may go to space on someone elses dime, and then think about how much the cost would change if equipment was considered unreliable.

With robots you have issues of time delays for decision making that you don't have with a human locally.

The meetings and bureaucracy at nasa probably cost less than the above.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

Because, like with Sunshine, if a movie is couched as realistic, and 'looks' realistic, then the layman will assume it is realistic. This annoys those who know just how wrong things actually are, especially when things are needlessly inaccurate. If your error could have been solved by 30 seconds on Wikipedia, then that's not making a vital deviation to allow the plot to advance, it's just not caring. And not caring about your film is rarely the sign of a good film.

Of spacewalks in 2013, aside from the one that got cut short due to a suit problem, not a single one was shorter than five and a half hours. The longest was seven and a half.

The truth is that they go so slow they just are not going to make a compelling movie. I don't want to watch five and a half hours of realistic spacewalk, it will quickly get boring. I accept some stretching of reality. And remember that NASA can use that stretching as an excuse to do some education for those who are interested.

Those of you who are experts in orbital mechanics—or perhaps regular Kerbal Space Program players—are likely nodding your heads in agreement, but this bit of jargon requires some explanation for the rest of us.

I got a smile out of this. Yes, if you have even a passing interest in building stuff and space exploration, are interested in space and orbital mechanics, and find amusement in multiple (and I mean multiple) accidental explosion, take the time to check out Kerbal Space Program. If you haven't heard of it before, there is a great thread in the GESC forum.

Excellent article. I am one of those people who's eye twitches when the movies get the science wrong. For example I don't think I've been able to watch The Core without yelling at the TV (probably the worst example of movie physics ever). Hopefully I can watch this with a mostly intact suspension of disbelief, but yeah, the orbital transfer thing has bothered me since I saw the first trailer.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

I think it's incredibly precious to expect a non-documentary film on general release to the unwashed masses to represent one's field with 100% accuracy.

Name one film released this side of 2000 that was 100% accurate. Most of them are at about 20%, and scifi at about 1%. If a film hits even 80% it's done a spectacular job.

Finally, a question for the people who know: how do the suits communicate? Is it point to point, or do they need to relay through the shuttle/ISS?

There are multiple communication modes, including suit-to-suit and relay via vehicle. The only way the astronauts can talk to the ground, though, is by relaying through their spacecraft.

Robert Heinlein taught me trick of private communications between astronauts can be had by pressing their helmets together to transfer sound energy from one visor to another when I was a kid. Unfortunately, I've never been off planet to test that out.

I am not a rocket scientist, just a Kerbal Space Program player. The other major factor in an orbital rendezvous besides having enough delta-v is timing. Let's say Clooney does have just enough propellent in his magic rocket pack.

They probably would have needed to wait some non zero number of orbits for the timing on their maneuvers to be right. They most likely would have run out of air before even using their propellent.

You could just make the maneuvers right away, and get into a matching orbit, but your target would be in the same orbit on the other side of the planet from you.

Now you have to make another set of maneuvers that leave your apoapsis touching the desired orbit but lower your periapsis below it. This allows you to "catch up" to your target because as the article mentions, while you are lower in orbit you are going faster.

But then at this point you still have to usually wait a significant number of orbits to catch up, and burn more delta-v bringing your periapsis back up to the desired orbit when you do.

"What is drama but life with the dull bits cut out?" ~ Alfred Hitchcock

I'm sure that when George Clooney watches a video by NASA, he gets irritated by people stuttering, the uhs, the ums, and so on. When cinematographers watch them, they probably get annoyed by jump cuts, odd angles, poorly lit scenes, and so on. Let's not forget the message of the last few paragraphs that this is, in the end, a movie, not a NASA training video.

I'm reminded of the time I was watching "Saving Private Ryan" with my cousin. I have seen the movie several times, and so has he. But this time he kept pausing the movie, point out the various errors ("you can see the microphone there", "you can see the camera there"). Needless to say it was utterly miserable experience. Luckily we only watched the first 15 minutes of it. Luckily I tried not to pay attention to the details he kept pointing out and I have since forgotten them, as they would have made any subsequent viewing that much worse, as my attention would be drawn to them.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

I think it's incredibly precious to expect a non-documentary film on general release to the unwashed masses to represent one's field with 100% accuracy.

Name one film released this side of 2000 that was 100% accurate. Most of them are at about 20%, and scifi at about 1%. If a film hits even 80% it's done a spectacular job.

Repeat after me: fiction isn't fact.

There's a stretch between "not as it is done in reality" , "not rational but physically possible" and "physically impossible".

A fiction can be not 100% accurate and still retain some plausibility. That said, this movie seems to touch only the second category, which is not that bad.

Well that would be just dumb to try to do plane changes. Have they not watched any Start Trek movies? You just plot an intercept course and shoot yourself off in exactly the right direction at exactly the right millisecond. You can even use explosive decompression of an airlock in a pinch.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

For me, it's the science teacher in me that goes nuts. Try as we might, it's really, really hard to get kids mind from the huge, dramatic Hollywood version of science to the often much more sedate form of real science. That's not to say that there isn't cool stuff in real science, it's just not as dramatic (go figure) as the movies.

You have no idea how many times I've had to debunk Armageddon, 2012, The Day After Tomorrow, The Core, Volcano, Dante's Peak, and just about every other disaster movie known to man. (Brosnan outrunning a pyroclastic cloud in a pickup with no tires? Yeah, not gonna happen. We would end up with crispy Brosnan long before the cool busted arm moment.)

Because, like with Sunshine, if a movie is couched as realistic, and 'looks' realistic, then the layman will assume it is realistic. This annoys those who know just how wrong things actually are, especially when things are needlessly inaccurate. If your error could have been solved by 30 seconds on Wikipedia, then that's not making a vital deviation to allow the plot to advance, it's just not caring.

If you don't know it's an error, it takes more than 30 seconds to check. Should every single word, clause, sentence and paragraph of every book, play and film be minutely checked for errors by a team of a hundred or so subject matter experts?

They did employ experts, and they do care. They're just not neurotic about it. Chasing 100% is a psychological disorder.

"Gravity 2: The Congressional Inquiry". Priceless and would probably watch it too.I don't know why but I greatly enjoy going over the Rogers and CAIB reports. There is something fascinating in understanding how and why complex systems fail. My next on the list to read is Fukushima NAIIC's report.

Ok Mr SmartyPants NASA guy, 4.3 pounds of pressure eh? Aren't we supposed to be in metric? I think you meant 43 decipounds.

Nope, he was simplifying it -- I'm sure he well knows that pressure isn't measured in "pounds" even using US standard measures, but in PSI. He really meant 29.65 kPa, but nobody in the US would have understood what he was talking about...

Lee Hutchinson / Lee is the Senior Reviews Editor at Ars and is responsible for the product news and reviews section. He also knows stuff about enterprise storage, security, and manned space flight. Lee is based in Houston, TX.